WASHINGTON — When you're watching the Super Bowl next month, you might ponder whether that can of your favorite brew is costing you a little more because some investment bank is hoarding aluminum.

Bank trading in physical commodities such as oil, aluminum and energy was the subject of a congressional hearing last week as lawmakers questioned whether this activity, part of the deregulatory push in the 1990s, was in the best interests of the public.

The members of the Senate Banking subcommittee weren't too happy with the answers they got from regulators.

When an official of the Federal Reserve, which is supposed to weigh the benefits to the public of bank trading of commodities, said the Fed's primary concern in supervising this activity was the safety and soundness of the banking institution and the possible risk to the financial system, Rhode Island Democrat Jack Reed took exception.

"So, the public interest aspects of the test sort of go by the wayside," Reed commented.

"That's the way it's set up in the statute," responded Michael Gibson, director of banking supervision and regulation at the Fed.

Sherrod Brown, D-Ohio, chairman of the subcommittee on Financial Institutions and Consumer Protection, noted that at a July hearing on the same subject an executive of MillerCoors said actions by banks cost his company tens of millions of dollars in excess premiums over the last several years, and cost aluminum users $3 billion in one year alone.

The July hearing came after a report in The New York Times chronicled in detail how Goldman Sachs shuttled tons of aluminum between warehouses, holding back sales to boost the price.

The Fed, in one of those remarkable Washington coincidences, filed a notice just a day before last week's hearing that it was considering new restrictions on bank trading of physical commodities and solicited public comment.

"The Fed's proposal yesterday is a timid step," Brown said at the hearing. "It was too slow in coming, and there is still too much that we do not know about these activities and investments."

Elizabeth Warren, D-Mass., also complained about the delay. "We already have ample evidence," she said, "that the Fed needs to place additional restrictions on how banks trade and warehouse physical commodities to reduce systemic risk and protect consumers from market manipulation."

Warren asked Gibson if a separation of commercial and investment banking, as she recently proposed, would relieve the Fed from deciding banks could trade zinc but not aluminum or how much insurance an oil tanker should carry. The Fed official agreed it would since these would no longer be permitted activities for regulated bank holding companies.

"I have to say that sounds pretty appealing to me," Warren said.

In its notice on possible rulemaking, the Fed cited a number of catastrophic events involving commodities — from the Gulf oil spill to the Fukushima nuclear leak, as well as the August derailment in Canada of a shipment of crude oil that killed 47 people and the potentially disastrous accident involving another train shipment of oil in North Dakota in late December.

"Catastrophes involving environmentally sensitive commodities may cause fatalities and economic damages well in excess of the market value of the commodities involved or the committed capital and insurance policies of market participants," the Fed notice said in discussing potential risks to banks trading in these commodities.

The deadline for public comment on the Fed's notice is March 15, though typically comments are accepted well after that date. In any case, it would likely be months before the Fed was ready to propose draft rules, which would then be subject to another round of comment before being finalized.

It is a laborious and bureaucratic process, but the very filing of the notice indicates that the Fed is likely to do something, and Gibson affirmed this in his testimony. "We expect to engage in additional rulemaking in this area," he said.

The knowledge that the Fed is getting ready to impose new rules has prompted some of the big banks — JPMorgan Chase, Morgan Stanley and Goldman Sachs — to begin scaling back their commodities activities.

Given the political pressure applied through hearings like the one last week, the Fed will not be allowed to kick this can any further down the road — though obviously any action will be too late to bring down aluminum prices for this year's Super Bowl.

Darrell Delamaide has reported on business and economics from New York, Paris, Berlin and Washington for Dow Jones news service, Barron's, Institutional Investor and Bloomberg News service, among others. He is the author of four books, including the financial thriller Gold.